1. Field of the Invention
The present invention relates to a method to reduce insulin resistance and improve glucose tolerance. Particularly, the present invention provides a method to reduce insulin resistance and improve glucose tolerance by administering Parabacteroides goldsteinii. 
2. The Prior Art
According to the World Health Organization, the global incidence of type 2 diabetes mellitus in adults has more than doubled since 1980 to reach worldwide epidemic status. In 2014, it was estimated that 8.5% (422 million) of the human population had type 2 diabetes. Diabetic individuals are at increased risk of developing blindness, kidney failure, hypertension, heart attacks and strokes, which may reduce quality of life and lead to premature death. Insulin resistance, a condition in which the cells of the body respond poorly to insulin, may occur prior to type 2 diabetes and lead to fatigue and various metabolic disorders (i.e., metabolic syndrome). While aging and genetic inheritance may be involved in the development of insulin resistance and diabetes, the diabetes epidemic has been mainly attributed to poor nutrition, smoking and lack of physical exercise. Type 2 diabetes and its complications may therefore be prevented by lifestyle changes.
Many pharmaceutical drugs have been approved for the treatment of type 2 diabetes, including biguanides, alpha-glucosidase inhibitors, glucagon-like peptides, meglitinides, sodium glucose transporter 2 inhibitors, sulfonylureas, and thiazolidinediones. Unfortunately, these drugs often produce side-effects which may reduce treatment efficacy and patient compliance. Low-calorie diets and regular exercise are part of the strategies used to treat diabetes, but these approaches are difficult to implement and their long-term efficacy has been disappointing. For these reasons, alternative strategies to treat type 2 diabetes in a safe and effective manner are highly needed.
The gut microbiota participates in various physiological functions, such as energy regulation, nutrient absorption, vitamin production, and toxin neutralization. Gut dysbiosis has been noted in diabetic patients, but it remains unclear whether probiotic bacteria may be used to treat insulin resistance and type 2 diabetes.